The image of RST in the graph shown below is rotated 90°counterclockwise around the origin to form R'S'T'.

Please check the explanation.

Step-by-step explanation:

Let suppose we have a point P(x, y) if we rotate our point 90 degrees counterclockwise about the origin, the new coordinates of the image of the point P can be obtained by switching 'x' and 'y' and making 'y' negative.

In other words,

P(x, y) → P'(-y, x)

From the given triangle ΔRST,

The coordinates of the point S is:

According to the rule, if we have a point S(10, 1), after rotations of 90 degrees counterclockwise about the origin, the new coordinates of the image of the point S(10, 1) will be:

S(10, 1) → S'(-1, 10)

Here,

S'(-1, 10)  is the image of the original point or pre-image point S(10, 1).

Therefore, the y-coordinate of the point S' is: 10